Galvanometer to ammeter/voltmeter

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Homework Help Overview

The discussion revolves around converting a galvanometer into an ammeter and a voltmeter, focusing on the calculations for shunt and series resistances. The problem involves understanding the relationships between current, resistance, and voltage in these conversions.

Discussion Character

  • Mixed

Approaches and Questions Raised

  • Participants discuss the calculations needed for converting the galvanometer, questioning the correct values for full-scale deflection current and the corresponding resistances. There is an exploration of the formulas related to shunt and series resistances.

Discussion Status

Some participants have confirmed the calculations for the ammeter conversion, while others are seeking clarity on the voltmeter conversion. There is a mix of agreement and uncertainty regarding the approaches taken.

Contextual Notes

Participants are working within the constraints of the problem statement, which specifies the galvanometer's resistance and full-scale deflection current. There is an ongoing discussion about the assumptions related to these values.

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Homework Statement



The resistance of a galvanometer coil is 25ohms and the current required for full scale deflection is 500μA.
a) explain how to convert the galvanometer to an ammeter reading 20mA full scale, and compute the shunt resistance
b) explain how to convert the galvanometer to a voltmeter reading 500mV full scale, compute the series resistance

Homework Equations



V=IR
IfsRG= (Ia-Ifs)Rsh
Rsh=(RGIfs)/(Ia-Ifs)

The Attempt at a Solution

RG=25ohms

a)
does Ifs=0.02 or 0.0005A

0.0005A * 25ohms = ( 0.02A- 0.0005A) Rsh ??
Rsh=0.641

b)
 
Last edited:
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Your value for (a) looks okay. How will you approach (b)?
 
idk VV=Ifs(Rsh+Rh)
 
(0.5/0.0005) -25 = 975 ?
 
Looks good.
 
cool beans
 

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